ผมได้ลองผิดลองถูกจนเหนื่อยแล้วครับ ทำมา 2 วันเต็มจริงๆ พยายามจนเริ่มท้อแล้วครับ พี่ๆๆช่วยผมหน่อยครับ รายละเอียดด้านในโปรดอ่านครับ

Public Class fmRegister

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Dim conStr As String = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=D:\PoundManagement\PoundManagement\db.mdf;Integrated Security=True;Connect Timeout=30"
        Dim connection As New SqlConnection(conStr)
        connection.Open()
        Dim sql As String = "SELECT * FROM registerP WHERE txt1 = '" & Me.TextBox1.Text & "' AND txt2 = '" & Me.TextBox2.Text & "' AND txt3 = '" & Me.TextBox3.Text & "' AND txt4 = '" & Me.TextBox4.Text & "' AND txt5 = '" & Me.TextBox5.Text & "' AND txt6 = '" & Me.TextBox6.Text & "'"
        Dim command As New SqlCommand(sql, connection)
        Dim result As SqlDataReader = command.ExecuteReader()

        If (result.Read()) Then
            Dim sql1 As String = "UPDATE registerP SET status = '" & Me.TextBox7.Text & "' WHERE txt1 = '" & Me.TextBox1.Text & "' AND txt2 = '" & Me.TextBox2.Text & "' AND txt3 = '" & Me.TextBox3.Text & "' AND txt4 = '" & Me.TextBox4.Text & "' AND txt5 = '" & Me.TextBox5.Text & "' AND txt6 = '" & Me.TextBox6.Text & "'"
            Dim command1 As New SqlCommand(sql1, connection)
            command1.Parameters.AddWithValue("status", TextBox7.Text)
            If command1.ExecuteNonQuery() = 1 Then
                MessageBox.Show("ลงทะเบียนผลิตภัณฑ์เรียบร้อย", "ขอขอบคุณ", MessageBoxButtons.OK, MessageBoxIcon.Information)
                connection.Close()
                Me.Hide()
            End If
        Else
            MessageBox.Show("หมายเลขผลิตภัณฑ์ไม่ถูกต้อง หรือ การลงทะเบียนล้มเหลว โปรดลองอีกครั้ง", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning)
            connection.Close()
        End If
    End Sub

Private Sub TextBox7_TextChanged(sender As Object, e As EventArgs) Handles TextBox7.TextChanged
        TextBox7.Visible = False
    End Sub